And indeed, the problem is with gtkam (if you use the package from Marathon) - it requires libgphoto-hotplug which was provided by old libgphoto-common package but was dropped from the new one.
I have built gtkam for contrib repo of ROSA Desktop Fresh and replace "libgphoto-hotplug" with more general "gphoto2" requirement. Please wait a little while the new version (gtkam-0.1.18-3) appears on mirrors, then try to install it and update your system again.